The present disclosure relates to vehicle safety and protection systems, and more specifically, to side-impact protection systems based on pre-crash sensing.
Side-impact protection systems are now being provided in vehicles to reduce the risk of injury to the vehicle occupants during side collisions. Many of these protection systems use airbags that get deployed a few milli-seconds after a collision occurs, with the airbags softening the impact to the vehicle occupants and also absorbing some of the crash energy during the impact. For sensing an approaching vehicle or an object, called as a bullet vehicle or a bullet object, many cars are equipped with detection systems that include radar sensors, such as those used in vehicle blind-spot detection systems, to provide information signals preceding an impact threat.
A bullet vehicle has a specific velocity as it approaches the vehicle being affected by the collision (hereinafter referred to as ‘target vehicle’). Typically, for protection systems using airbags, during side collisions, the target vehicle door's velocity continues to increase until the airbag which is mounted on the target vehicle's door, gets fully deployed and contacts the target vehicle's occupant sitting next to the door. The target vehicle's occupant picks up a velocity inwards and away from the side door, when the airbag contacts the occupant. The target vehicle also acquires a lateral velocity in the direction of impact. Finally, all the three velocities, i.e., the bullet vehicle's velocity, the occupant's velocity and the target vehicle's velocity, acquire a common value at a certain time.
During a side-impact, deployment of an airbag as early as possible can significantly reduce the amount of impact injury to a side occupant. Specifically, during a side collision, the rate of increase of the occupant's lateral velocity (i.e., the occupant's lateral acceleration), which depends on the occupant's interaction with the airbag is directly proportional to the impact force experienced by the occupant. A reduction in occupant's lateral acceleration during a side impact helps to reduce the risk of injury to the occupant. Attempts have been made in the art along this direction, by utilizing existing crush space between the side-impact door and the occupant. For example, some disclosures have been directed towards increasing the stiffness of the side impact protection structures and mechanisms, to absorb maximum crash energy, and thus reduce the occupant's acceleration. However, such attempts to reduce the occupant's lateral velocity increment rate (i.e., occupant's lateral acceleration) add significant weight and other design complexities to the vehicle.
Therefore, there exists a need for a side-impact protection system that can help to reduce the injury risks during side-impacts.